Male and female luer taper fittings are conventionally employed to connect disposable medical devices (such as a syringe and a needle) in a liquid and air leakproof manner. After they have been connected (pushed together), luer taper fittings remain together solely due to friction between their mating tapered surfaces. They may readily be disconnected by twisting and pulling the female and male fittings away from each other.
Various additional design components have been employed with luer taper fittings to increase their connection strength. Increased connection strength is needed, for example, to accommodate high pressure fluid flow through the connected fittings or for extra protection against the loss of high risk fluids such as a patient's blood in a hemodialysis procedure. Luer lock fittings are an example of this class of "enhanced" luer taper fittings.
Conventional female luer lock fitting 5 is shown in FIG. 1. Conventional male luer lock fitting 6 is shown in FIG. 2. Tapered nozzle 10 of lock fitting 6 is dimensioned to fit tightly inside tapered socket 11 of lock fitting 5 as fitting 6 is screwed onto fitting 5. When lock fittings 5 and 6 are connected, fluid may flow between central fluid passage 16 of fitting 6 and central fluid passage 17 of fitting 5. Fitting 6 includes locking ring 12 (sometimes referred to as a "collar"), which has an internal threaded portion 14. Fitting 5 has an annular lug 15, which is dimensioned so that lug 15 may be screwed into threaded portion 14 of fitting 6, as nozzle 10 is inserted into socket 11.
Conventionally, luer lock ring 12 may be fixed 0 to nozzle portion 10 as shown in FIG. 2, or it may be a separate component from the nozzle that is free to move rotationally but not longitudinally (a "free/restricted ring"), or free to move rotationally and partially free to move longitudinally (a "free/partially restricted" ring) in which case the distal ring threads are still in contact with the female lugs after the ring has been untwisted until it encounters its restriction, or free to move both rotationally and longitudinally (a "free ring") in which case the ring threads may be completely unscrewed from the female lugs before the ring encounters any longitudinal restriction.
Industry standards have been established (and others proposed) for standardizing the dimensions of luer lock fittings (of the fixed type shown in FIGS. 1 and 2, the free type shown in FIG. 2a, and the free/partially restricted type shown in FIGS. 9 and 10). One such standard is the American National Standard Institute/Health Industry Manufacturers Association MD70.1 standard, adopted in 1983 (hereinafter, the "ANSI/HIMA" or the "ANSI/HIMA MD70.1" standard), and another is the ISO/DIS 594-2 proposed standard (hereinafter, the "ISO" standard).
In FIG. 2, fixed ring 12 is shown to be integrally formed with nozzle 10. Alternatively, ring 12 and nozzle 10 may be separately manufactured, and then attached together to form a rigid assembly. To connect male fitting 6 of FIG. 2 with female fitting 5 of FIG. 1, threads 14 of fitting 6 must be screwed onto lugs 15 of fitting 5.
In the case of a free ring (with both rotational and longitudinal freedom) such as that shown in FIG. 2a, two steps must be performed in order to separate a male free ring fitting from a female fitting (such as fitting 5 shown in FIG. 1) after they have been screwed together. First, the fittings must be unscrewed until lugs 15 of the female fitting are released from threads 24 of free ring 22. Then, nozzle 20 and female socket 11 must be twisted and pulled apart (since the tip of nozzle 20 will still remain in contact with socket 11 immediately after lugs 15 have been released from threads 24) as in the case of conventional luer slip male/female fittings.
The ISO standard requires (among with its other requirements) that the length L of nozzle 20 protruding beyond the end of ring 22 (in its forward position) be not less than 2.10 mm. The ISO standard also specifies that the minimum total length E of nozzle 20 is 7.50 mm, and that the minimum total length F of socket 11 is 7.50 mm.
In FIG. 2a, ring 22 is free to rotate about longitudinal axis Z relative to nozzle 20. Ridge 25 of nozzle 20 restricts upward longitudinal translation of ring 22, to prevent ring 22 from decoupling from nozzle 20, but ring 22 is completely free to translate longitudinally downward relative to nozzle 20. The tip portion of nozzle 20 is conventionally used to puncture (or "spike") IV fluid container access ports, since ring 22 may be retracted out of the way during the puncturing process.
An advantage of a "free ring" male fitting is that it may be mated and locked with a female fitting (and unmated and unlocked from the female fitting) without causing any pronation of the tubes attached to the fittings. This is crucial in preventing kinking or other problems with the tubing. However, a serious disadvantage of conventional free ring male fittings is that they provide no leverage to a user attempting to decouple their nozzle from a female 10 luer fitting after the threads of the free ring have been untwisted from the female luer fitting lugs. Thus, free ring made luer connectors of the type shown in FIG. 2a are difficult to disconnect from female luer fittings.
Yet another conventional male connection fitting (of the "free/partially restricted" type) is shown in FIGS. 9 and 10. Nozzle 400 is shown in its extended position relative to ring 420 in FIG. 9, and in its retracted position in FIG. 10. In FIG. 9, the right end surface 431 of ring 420 abuts shoulder 413 of nozzle 400 so that the top portion of nozzle 400 extends a distance M' leftward from left end surface 433 of ring 420. In FIG. 10, nozzle 400 has been retracted toward the right until shoulder 434 of nozzle 400 abuts ridge 432 of ring 420, so that nozzle 400's tip portion extends a lesser distance L' leftward from left end surface 433. To facilitate decoupling of the FIG. 9-10 fitting from a female luer fitting (not shown), length M' must be sufficiently short that threads 426 of ring 420 are in contact with the lugs at the end of the female fitting in the FIG. 9 configuration (i.e., after ring 420 has been untwisted until end 431 abuts shoulder 413).
This restriction on the length M' allows the last untwisting force applied to ring 420 to be transformed into a "push-off" force for assisting a user to overcome friction between nozzle 400's outer tapered surface 424 and a female luer fitting, in order to decouple nozzle 400 from the female luer fitting. However, this restriction on the length of M' renders tip portion 425 of nozzle too short for spiking commonly used IV fluid container access ports.
In hemodialysis and a number of other medical operations employing luer lock fittings, the luer lock fittings are employed to provide a leak-proof blood flow passage between, for example, a patient access device and an extracorporeal circuit (male nozzle on circuit, female socket on access device). It is also necessary before or after such operations to spike a port in a saline bag with an IV administration set attached to the extracorporeal circuit in order to prime the circuit (before) and rinse the circuit of blood (after). It would be convenient if the male luer lock nozzle could be used to spike the fluid bag port directly, and if the same male luer lock could later be connected to the female luer lock during the same medical operation.
Currently, the only luer lock assembly that can also spike a bag is the "free ring" male luer lock. However, this type of conventional male luer lock is difficult to decouple from a female luer fitting (as explained above).
An example of a commonly used conventional medical fluid container port ("bag port") is shown in FIG. 3. Bag port 200 of FIG. 3 has a cylindrical end portion 201 and a larger diameter body portion 202, which define a shoulder 204 between portions 201 and 202. Membrane 203 separates portions 201 and 202 in order to retain fluid 205 within portion 202. Bag port 200 may be opened by translating a puncturing member toward the left along port axis 206 to pierce (or "spike") membrane 203 (as shown in FIG. 3, which will be discussed below). In one commonly used embodiment of bag port 200, distance D between membrane 203 and the right end of end portion 201, is substantially equal to 9.0 mm, and inner diameter C' of portion 201 is substantially equal to 5.1 mm.
In current practice, there are a number of nonluer lock, male nozzle connectors which are 10 dimensioned properly within the standards to puncture membrane 203 and be frictionally retained by the inner lumen of end portion 201 until removed by the health care worker.
However, conventional male luer locks (whether or not they satisfy the ANSI/HIMA standard) having fixed locking rings (such as the FIG. 2 device), or conventional rings of the "free/restricted" and "free/partially restricted" types, are not capable of spiking the commonly used conventional fluid bag ports. This is because the nozzle of this type of such conventional male luer lock has insufficient length beyond the end of the locking ring (i.e., length L beyond locking ring 12 in FIG. 2) to pierce the bag port membrane (i.e., membrane 203 in FIG. 3), when the end of the locking ring has translated into engagement with the shoulder (shoulder 204 in FIG. 3) between the end and body portions of the bag port.
Some conventional "free ring" male luer lock fittings have been designed with lock rings having sufficient longitudinal freedom of movement, and with male fittings sufficiently long and with a sufficiently narrow transition length, to spike commonly used conventional fluid bag ports (such as that shown in FIG. 3) and be frictionally retained in such ports during the priming and/or rinse back procedure. However these conventional "bag spiking, free ring" male luer locks have the following disadvantages. First, their longitudinal transition portions are so long and narrow that, when connected to female luer locks, the connectors undesirably increase the resistance to fluid flow through the luer connection (and hence the fluid pressure drop through the luer connection). Second, conventional "bag spiking, free ring" male luer locks provide 10 users no mechanical leverage when they attempt to disconnect such male luer locks from female luer locks (as discussed previously). Hemodialysis users, for example, have experienced difficulty in pulling apart such a free ring male lock's nozzle from a female lock's socket (after the female lock has been unscrewed from the threads of the male lock's free ring) because of the increase mating friction due to swelling of the parts into each other during the hemodialysis procedure (typically having two-to-six hour duration, and occurring at 37 degrees Celsius).
It would be desirable to design a bag spiking male luer fitting capable of giving the same significant mechanical advantage in pushing off (decoupling) a female fitting from a male nozzle as it has in connecting with a female fitting. However, it has not been known until the present invention how to combine the bag spiking advantages of conventional free ring male luer locks with the low fluid flow resistance and unlocking leverage of conventional "free/partially restricted" male luer locks. Nor has it been known until the present invention how to design a male luer lock to avoid the described limitations and disadvantages of conventional "bag spiking, free ring" male luer locks, while still being capable of piercing commonly used fluid bag ports.